[media] rc-core: improve the lirc protocol reporting

Commit 275ddb40 removed the lirc
"protocol" but kept backwards compatibility by always listing
the protocol as present and enabled. This patch further improves
the logic by only listing the protocol if the lirc module is loaded
(or if lirc is builtin).
Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/rc/rc-main.c

@@ -828,6 +828,23 @@ struct rc_filter_attribute {
 		.mask = (_mask),					\
 	}
 
+static bool lirc_is_present(void)
+{
+#if defined(CONFIG_LIRC_MODULE)
+	struct module *lirc;
+
+	mutex_lock(&module_mutex);
+	lirc = find_module("lirc_dev");
+	mutex_unlock(&module_mutex);
+
+	return lirc ? true : false;
+#elif defined(CONFIG_LIRC)
+	return true;
+#else
+	return false;
+#endif
+}
+
 /**
  * show_protocols() - shows the current/wakeup IR protocol(s)
  * @device:	the device descriptor
@@ -884,7 +901,7 @@ static ssize_t show_protocols(struct device *device,
 			allowed &= ~proto_names[i].type;
 	}
 
-	if (dev->driver_type == RC_DRIVER_IR_RAW)
+	if (dev->driver_type == RC_DRIVER_IR_RAW && lirc_is_present())
 		tmp += sprintf(tmp, "[lirc] ");
 
 	if (tmp != buf)